Method and apparatus for hydrolyzing cellulosic materials



June 22, 1954 L. c. WALLACE METHOD AND APPARATUS FOR HYDROLYZING CELLULOSIC MATERiALS Filed Feb. 16, 1951 3 Sheets-Sheet 3 (mm-min Patented June 22, 1954 UNITED STATES PATENT OFFICE METHOD AND APPARATUS FOR HYDRO- LYZING CELLULOSIC MATERIALS Application February 16, 1951, Serial No. 211,274

16 Claims.

This invention relates to a method and apparatus for hydrolyzing cellulosic materials to form sugar, furfural and lignin and is particullarly directed toward hydrolyzing such materials as saw dust, wood chips and the like, and has for an object the provision of such a method and apparatus in which the rate of reaction and the net yield of sugar is greatly increased.

Another object is to provide a method and apparatus of the character designated which shall include means for rapid removal of heat-labile sugars and volatile products thus permitting an increase in the severity of processing conditions to obtain better yields and more rapid processing.

A further object is to provide a method and apparatus of the character designated in which a continuous countercurrent washing of the partially hydrolyzed cellulosic materials with fresh hydrolyzing solution is obtained thus removing the maximum amount of soluble sugar.

A further object is to provide a method and apparatus of the character designated whereby there is a bed of constantly renewed cellulosic material which acts as a filter bed, providing a cleaner sugar liquor.

A further object is to provide apparatus for hydrolyzing cellulosic materials in which the investment, maintenance and the labor required to operate the same is greatly reduced.

A further object is to provide a continuous method and apparatus for hydrolyzing cellulosic materials which shall produce liquors containing a maximum percentage of sugars thus reducing the cost of evaporating the same to molasses.

A still further object is to provide a method and apparatus of the character designated which shall produce a product of uniform quality.

Heretofore in the art to which my invention relates, so far as I am aware there has been no commercially successful continuous process for the hydrolysis of wood or other cellulosic materials. Numerous batch processes have been devised for the hydrolysis of wood, but such processes have not been economical for the production of molasses or wood-sugar due to the low sugar concentration obtained. Such a product is not objectionable for fermentation, but is unsatisfactory for evaporation to molasses because of the high cost of evaporation. Also, batch processes are expensive to operate due to the fact that blowing-down and recharging accounts for approximately 25% of the total operating time, and consequent loss in capacity of the reactor; also much heat is lost in blowing down and recharging.

I have devised a continuous method and apparatus for hydrolyzing cellulosic materials whereby a product is obtained which is not only suitable for fermentation to ethanol or butanol and acetone but may also be economically concentrated to a molasses for stock feed or used as food for growing high protein fodder yeast. Purification of the sugars thus produced yields a product fit for human consumption. Also, my apparatus operates continuously thus maintaining the apparatus under full pressure and utilizing the full capacity of the reaction chamber at all times.

Briefly my invention comprises continuously introducing the cellulosic material at the top of a vertical reaction chamber of special shape and having a vertical feed screw at the top and lignin discharge means at the bottom thereof. A suitable hydrolyzing solution is introduced continuously at the bottom of the reaction chamber, thus causing the liquid to flow in a direction countercurrent to the flow of the cellulosic material. Volatile materials and liquor are continuously drawn off adjacent the top of the reaction chamber while the lignin is continuously discharged at the bottom thereof.

Apparatus embodying features of my invention is illustrated in the accompanying drawings forming a part of this application in which:

Fig. 1 is a side elevational view of the apparatus partly broken away and in section;

Fig. 2 is a diagrammatic elevational view of apparatus for carrying out the process;

Fig. 3 is a typical graph showing degrees of hydrolysis obtained at spaced intervals from top to bottom of the reaction chamber;

Fig. 4 is a detail sectional View showing the bottom of the reaction chamber and lignin discharge valve;

Fig. 5 is a plan View of the apparatus with the reactor chamber removed and taken along the line V-V of Fig. 4;

Fig. 6 is a diagrammatic elevational view of apparatus for controlling the liquid level, partly broken away and in section; and

Fig. '7 is an enlarged View of the control valve shown in Fig. 6.

Referring now to the drawings for a better understanding of my invention, I show a feed hopper it for receiving the cellulosic material to be hydrolyzed. The cellulosic material may be green or dry, and drained, washed, pie-acidified or otherwise pre-treated. The cellulosic material is withdrawn from the hopper In by means of an approach screw II which is rotatably mounted in a horizontally extending housing !2. The discharge end of the approach screw housing communicates with a vertically extending housing l3 tapered downwardly toward the lower end thereof. Rotatably mounted in the housing 3 is a feed screw M, which is also tapered. toward the bottom thereof. The feed rate is con trolled by adjusting the speed of the approach screw I i so that the material enters the tapered feed screw housing at a density of approximately 8 pounds per cubic foot, dry basis. The cellulosic material is compressed so as to form a steamtight plug adjacent the lower portion of the tapered screw housing :3. The compression ratio is controlled by the relative rates of rotation of the screws l l and M which maybe driven by any suitable source of power, not shown, through pulleys i5 and i5 respectively. Excess water, if present, is pressed out during the com pression and is discharged through slots 56 in the bottom of the approach screw housing 12.

The tapered screw housing i3 is mounted upon and discharges into a reaction chamber II. The upper end of the reaction chamber 1'. hasdownwardly flaring side walls, as indicated at 20, to facilitate downward flow of solids against upwardly flowing fluids. Preferably, the walls of the reaction chamber are cone shaped adjacent the top thereof, as indicated at is. Also, the walls at the lower end of the reaction chamber are flared outwardly from the bottom thereof to form a collecting section 19.

The reaction chamber I? is preferably made separable as at 20' to facilitate assembly and dis mantling of the apparatus. Annular flanges Ila and llb are provided for securing the upper and lower sections together. Secured to the lower end of the tapered screw housing 13 and spaced from the cone shaped portion i8 is a filter cone or screen 2i having a lower annular flange it which fits between the flanges Na and Ill) thus securing the cone M in place. The compressed cellulosic material from the tapered screw housing 13 enters the upper portion of the filter cone 2i and expands rapidly while passing therethrough. Pre-steaming of the chips occurs at this point thus removing any residual air and prepares the cellulosic material for imbibing the hydrolyzing solution. Also, presteaming removes turpentine and volatile oils from pine and converts pentosans from hardwoods into desirable furfural. Liquor and vapors escape from the reaction chamber into an annular chamber 25 defined by the filter cone 2i and the cone shaped wall [8. Communicating with the chamber 25 through the upper portion of the wall 58 is a vapor off-take conduit 22 having a regulating valve 22 therein. The conduit 22 is employed for purging air from the chamber 25. Communicating with the chamber 25 through the lower portion of the wall is is a discharge conduit 23 for liquor and volatile materials. The conduit 23 has a discharge valve 24 therein which is operated by an automatic level controller 25 to be described hereinafter. The vapor conduit 2 2 and the liquor discharge conduit 23 com-- municate with a liquor flash tank 26 where the dilute sugar liquor is collected in a tank 29. The vapors pass from the liquor flash tank 28 through a conduit 3! to a scrubbing tower 32 where their condensible and soluble constituents are removed, as is well understood, and collected in a suitable container 33.

It is desirable to remove the heat labile sugars and vapors as they are formed due to the fact n at) that conditions of temperature and acid concentrations which will hydrolyze cellulose to sugar will also decompose the sugars thus formed. In general the more easily hydrolyzed portions of the cellulose give rise to the more easily decomposed sugars. However, the rate of cellulose hydrolysis increases more rapidly with severity of conditions than does the rate of sugar decomposition. Accordingly by increasing the severity of processing conditions a more rapid processing and better yields are obtained.

The descending cellulose material acts as a filter bed to prevent lignin fines from reaching the upper filter screen 2| thus making it possible to provide non-clogging openings 33 in the filter cone 2!. The openings 30 are preferably around inch in diameter and are drilled at an angle of approximately 45 with respect to the walls of the filter cone 2| and slope inwardly in the direction of the flow of cellulose material. The moving cellulosic material tends to scrape out any splinters or the like which might be lodged in the filter cone.

As the cellulosic material enters the reaction chamber I! and contacts the upwardly flowing hydrolyzing solution, a relatively stiff, coherent mass somewhat less dense than the fluid is formed. This mass is prevented from floating or bridging and binding by the positive downward force exerted by the tapered feed screw [4. Also, the negative slope of the upper reactor walls as indicated at 26 is such that the force from the tapered feed screw Hi can overcome friction between the cellulosic material and the walls even at high densities and high rates of feed.

As the cellulosic material moves downwardly through the reaction chamber I? it becomes progressively softer, smaller or more dense. The increase in density is due both to water-logging and to the fact that lignin is more dense than cellulose. By the time the material reaches the lower portion of the reaction chamber I! it is suiiiciently soft and dense to sink freely into the collecting section I9 where the lignin is thoroughly washed by the ascending fresh hydrolyzing solution. At the bottom of this zone, all that remains of the cellulosic material is granular lignin fines which settle into the lower portion of the collecting section l9 which is in the form of an inverted cone 34.

Attached to the bottom of the reaction chamber I1 and enclosing the cone 34 is a discharge housing 36. Mounted in the lower end of the discharge housing 36 is a bearing sleeve 35. Rotatably mounted in the bearing sleeve 35 opposite the cone 34 is an externally threaded gland 3'! adapted to fit an internally threaded portion 33 at the bottom of the bearing sleeve 35. Slidably fitting in the gland Bl is a poppet valve 39 having an enlarged upper end 4| of a size and shape to slidably engage the bearing 35 and seat against the discharge or lower end of the cone 34. The poppet valve is held in seated position by means of a back pressure spring 42 which surrounds the poppet valve between the upper end thereof and the gland 31. The pressure exerted by the spring 42 may be adjusted by means of the gland 31. The poppet valve 39 is opened briefly at timed intervals, by means to be described hereinafter, so as to retain pressure in the reactor and yet discharge the desired amount of lignin. Upon release of pressure, the lignin in the lower nd of the cone 34 explodes out of the reaction chamber due to the contained liquid therein which flashes into steam upon release periphery thereof.

of pressure at the valve. This prevents hanging and bridging of the lignin. Also, shock from the intermittent opening of the poppet valve causes the whole wood charge to move downwardly. The lignin passes from the discharge housing 36 through a conduit 43 to a suitable separator or lignin flash tank 44, thus eliminating undue hazards to the operator caused by poppet valve failure.

The means for opening the poppet valve 39 at timed intervals comprises a lever 46 pivoted intermediate its ends to a bracket 4'! which is secured to the bottom of the discharge housing 36 by means of bolts 45. One end of the lever 46 is pivotally connected to the lower end of the poppet valve 39. Rotatably mounted adjacent the other end of the lever 45 is' a roller 48. R- tatably mounted beneath the roller 48 on a shaft 49 is a cam wheel 5! having a cam 52 mounted thereon in position to engage the roller 48 and raise the adjacent end of the lever 49. It will be seen that each time the cam wheel 5! rotates, the poppet valve 39 Will be opened by the cam 52 and will close as the roller 48 disengages the cam 52 due to the pressure exerted by spring 42.

The cam wheel 5! is rotatably connected to a variable speed drive 59 by means of a sprocket chain 54 which passes over a sprocket 59 mounted on the shaft 49 and a sprocket 51 mounted on the variable speed drive shaft. The variable speed drive 53 is driven by a motor 58 through a shaft 59. The operation of the motor is controlled by an electrical circuit now to be explained.

Secured to the shaft 49 is a small cam wheel 6| having a cam 62 extending outwardly from the Pivotally mounted in position to engage the cam 62 is a switch 53 having contact points 54 and d5 biased toward closed positionvby means of a tension spring 61. It will be seen that the switch 63 will remain in closed position until its points are separated by the cam 62. Point 94 of the switch 63 is connected directly to a lead in wire 68. Also connected to the lead in wire 66 is one terminal of the motor 58 and a point 69 of a switch 'II. Switch II is biased toward open position by means of a tension spring 72. The other point 13 of the switch II is connected to a lead wire M which connects point 66 of the switch 93 to the lower terminal of a solenoid id. The switch H is closed at timed intervals by a small variable speed control motor TI having a rotating cam 13 disposed to engage and close the switch. A lead in wire I9 connects the upper terminal of the solenoid I6 to a point 3| of a switch 82, which is biased toward open position by means of a tension spring 83. The switch 32 is pivotally mounted beneath the solenoid and is operably connected thereto as at 34 thus causing the switch 82 to be closed when the solenoid is energized. The other point 86 of the switch 82 is connected to the motor 58, by a lead wire 85, thus completing the circuit thereto.

In operation the motor I7 continuously rotates the cam 78. When the switch II is closed by the cam 78 the circuit to the solenoid is complete through lines 68, I l and '19. As the solenoid is energized the switch 62 is closed, thus completing the circuit to the motor 58 through lines 68, 85 and 79. As the cam 18 moves to disengaged position the switch II is opened by the spring 72. At this time the switch 63 is closed thus keeping the solenoid energized and completing the circuit to the motor 59. The switch 63 remains in the closed position until it is opened by the rotating cam 62. After the cam I52 has opened the switch 63 it remains open and the circuit to the motor 58 is broken until the motor I! has again turned the cam 18 to engaging position with the switch II. It will be seen that by varying the speed of the control motor I7 the poppet valve 39 can be operated at any desired timed interval.

In Figs. 6 and '7 I show apparatus which may be employed to control the liquid level in the filter cone. Communicating with the filter chamber 25 adjacent the upper portion thereof is a conduit I94 which also communicates with a float chamber I95. A conduit I91 connects the lower portion of the filter chamber 25 to the lower portion of the float chamber I96.

Mounted at the top of the float chamber is a vertically extending bearing member I08 having an iron piston m9 disposed to move vertically therein. Extending downwardly from the piston I99 is a rod III having a float Il2 secured to the lower end thereof. Secured to the top of the bearing member I98 is a bracket II3 having pivotally mounted at its outer end a lever I I4. A permanent magnet I 56 is mounted at the lower end or" the lever H t and mounted at the upper end of the lever H4 is a mercury switch II'I having contact points IIS and H9. The contact point H2 is connected to a lead in wire I 2I. The contact point H9 is connected through a lead wire I22 to the lower terminal of a solenoid I23 having an armature I24. The upper terminal of the solenoid I23 is connected to a lead in wire I26. The lower end of the armature I24 is operatively connected to an air valve I2! now to be explained.

The air valve I27 includes a cylinder I28 having an opening through the top thereof for receiving the lower end of the armature I24. Secured to the lower end of the armature is a piston I29. The cylinder i28 is also provided with an air inlet port I3i, an exhaust port I32 and a power port I33. The piston I29 has a horizontally extending opening I34 which registers with the inlet port I3I when the piston is in the down position. Communicating with the opening H4 is a vertically extending opening I36. The opening I36 also communicates with the lower portion of the cylinder I 28 and the power port I33. Communicating with the upper end of the vertically extending opening I36 is a horizontally extending opening I31 which registers with the exhaust port I32 when the piston I29 is in raised position. The piston I29 is biased toward the raised position by means of a cornpression spring I38 positioned in the lower portion of the cylinder I28.

The power port I33 of the valve I2! is connected to an air chamber I 39 having a diaphragm MI extending horizontally across the central portion thereof. Extending upwardly through and secured to the diaphragm HiI adjacent the center thereof is a rod M2 which is biased toward raised position by means of a tension spring M3 positioned in the upper portion of the chamber I39. The lower end of the rod M2 is pivotally connected to a valve stem I44 which is operatively connected to the valve 24 in the outlet conduit 23.

From the foregoing description the operation of the liquor discharge apparatus will be readily understood. With the liquor at the lower liquor level the float H2 moves the iron piston I99 out of contact with the magnet H3. The mercury switch thus assumes its normal balance position, as shown in solid lines in Fig. 6, thus making contact between the points I It and I I 9 and complet- .ing the-circuit to the solenoid I23. With the solenoid energized thepiston I29 is moved-downward,

by the armature I24, to a position whereby the "opening I34 is in register with the opening I32 which receives compressed air from any suitable source, not shown. The air passes downward through the opening 136 into the power port I33 and then to the chamber I39. The compressed air forces the diaphragm MI and the rod I42-downwardly thus closing the liquor discharge valve 24.

When the liquor reaches the upper control level the float II2 moves the piston I89 near the magnet IIS thus causing the mercury switch to move '8 for the acid and only one inlet conduit for the steam, any desired number of such conduits may be employed.

The ascending liquor leaches residual sugars from the descending lignin and passes upwardly through the cellulosic material. Gravity mixing of the acid liquor is prevented by the continuous, unidirectional flow through the small interstices between the particles of cellulosic material.

The point at which complete hydrolysis is obtained should be as near the bottom of the reactor as possible so as to keep the reactor full at all times. In Fig. 3 of the drawings, the graph shows the degree of hydrolysis obtained in a typent points and preventing the same from mixing before entering the reaction chamber, the conduits areprotected against corrosion which would result from coming in contact with the hot dilute 'acid. While I have shown only one inlet conduit to the position shown in dotted lines in Fig. 6 ical run. The conditions were 1% sulfuric acid, thus breaking the circuit to the solenoid 23. at 150 pounds per square inch pressure, with a The spring I38 raises piston I29, thus closing through-put of i0 poundsper hour, dry wood, and the'inletport I3I and registering the opening I3! a liquor-wood ratio of 13.6, including steam and with the exhaust port I32. The air then escapes moisture in the wood. The reactor was cooled from the chamber I39 through the exhaust port down and samples taken at intervals from the thus allowing the spring I43 to lift the rod I42 top thereof. and-open the valve 24. Liquor is forced through It will be seen, by reference to portion A of the discharge conduit by gravity and the steam the graph, that approximately one third of the pressure which exists within the filter cone untotal potential sugar is hydrolyzed instantly. The til the lower level is again reached. The appa- 25 reaction then proceeds at a uniform rate, as repratus is then actuated automatically as described resented by portion B of the graph. Toward the .above to restart the cycle. latter part of the hydrolysis, as represented by The hydrolyzing solution, such as water and portion C of the graph, diffusion becomes cona suitable acid. for instance sulfuric acid, is trolling as the remaining cellulose is coated and pumped through pumps 81 and 88 respectively mixed with lignin. The solid line in Fig. 3 rep- .and mixed externally in a conduit 89. The di resents the observed results and the dotted line lute acid solution then passes through an inlet 9| represents the theoretical results obtained. adjacent the bottom of thereaction chamber H. The following table shows typical runs made The acid solution inlet 9| communicates with with a sulphuric acid solution having a concen- -a horizontally extending annular passage 92 tration of 1% (basis total liquor):

A t x C Concentra- (p S L) (Dry mg time Ratio dwelln 1g Sugar cent reducing lb./li1.; (M1n.) t1n1e(M1n.) Bm) sugar by analysis) 40 102 13.6 12 5. 1 a. 3 93 44 s. 7 s 12. e 7. a 68 60 7.9 12 9.0 5.9 192 as 44 5. 7 12 11.8 7. 7 200 13a 30 4. 0 12 16. a 10. 6

formed in an annular block .93 which is positioned From the foregoing it will be seen that I have between a flange 94 at the lower end of the redevised an improved method and apparatus for action chamber I! and a flange 96 on the cone do hydrolyzing cellulosic materials. When such 34. The block 93 is held in position by any suitmaterials are hydrolyzed in accordance with my able means such as bolts 95. Communicating invention, a dilute sugar liquor is produced havwith the annular passage 92 are a plurality of in an average sugar concentration of over 10%. spaced apart, upwardly extending openings 31 So far as I am aware prior methflds 0f d y which also communicate with the reaction chamea ing cellul s materials p u a su ar liquor her I! as at 98. Lying in a plane above the annuhaving an average sugar concentration of aplar passage 92 is a second annular passage 99 p y This increase in Sugar conand communicating with the annular passage centration reduces the evaporator investment 99 are a plurality of upwardly and inwardly ex and Operating Costs y more t 5 Also, the tending openings IOI positioned between the up- (in labor cost is reduced and the process reliability wardly extending openings 91 The openings m: is greatly increased by the inherently easy autocommunicate with the reaction chamber IT as at matic Control Of a Continuous Operation.

I02. Steam is introduced through an inlet cony Causing e cellulosic material to flow in duit I03 which communicates with the annular a direction countercurrent to the dilute acid passage 99. While I have shown the openings 97 to almost complete hydrolysis is obtained. The as extending upwardly and the openings in! as lignin is continuously Washed by the fresh acid extending upwardly and inwardly, it will be apthus assuring that practically all of the sugar parent that either or both of the openings may goes into solution. Also, there is no acid waste extend upwardly or upwardly and inwardly. By due to the fact that the fresh cellulosic material introducing the steam and dilute acid at diiler- 7-7 continuously contacts the spent acid solution. It

will also be seen that by having a constant and controlled input of hydrolyzing solution and oellulosic material that a uniform product is produced. Furthermore, by removing the heatlabilesugars and volatile products as they are :9 formed the severity of processing conditions may be increased to obtain better yields and more rapid processing.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications, without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be passed thereupon as are specifically set forth in the appended claims.

What I claim is:

1. The method of hydrolyzing cellulosic Ina-- terials comprising continuously bringing together under superatmospheric pressure cellulosic materials in countercurrent flow with a dilute hydrolyzing solution and steam whereby sugar, lignin and volatile products are produced, removing the sugar and the volatile products thus formed continuously adjacent the point the cellulosic materials are introduced, and removing the lignin substantially continuously adjacent the point said hydrolyzing solution and steam are introduced.

2. The method of hydrolyzing cellulosic materials comprising continuously bringing together under superatmospheric pressure cellulosic materials in countercurrent flow with a dilute hydrolyzing acid and steam whereby sugar, lignin and volatile products are produced continuously, removing the sugar and the volatile products continuously adjacent the point the cellulosic materials are introduced, and removing the lignin substantially continuously adjacent the point said acid and steam are introduced.

3. The method of hydrolyzing cellulosic materials comprising continuously bringing together under superatmospheric pressure cellulosic materials in countercurrent flow with dilute sulfuric acid and steam whereby sugar solution, lignin and volatile materials are produced continuously, removing the volatile materials and sugar solution continuously as they are produced adjacent the point the cellulosic materials are introduced, and removing the lignin substantially continuously adjacent the point said acid and steam are introduced.

4. The method of hydrolyzing cellulosic materials comprising introducing continuously cellulosic materials at the upper end of a downwardly moving column thereof while maintaining said column under superatmospheric pressure, introducing continuously a hydrolyzing solution and steam at the lower end of said downwardly moving column in counter-current flow to said cellulosic materials, expanding the volume of said cellulosic materials while passing the same in counter-current flow to said hydrolyzing solution and steam thus causing the cellulosic materials to imbibe the hydrolyzing solution and release lignin, sugar solution and volatile materials, removing continuously the volatile materials and the sugar solution adjacent the point of introduction of the cellulosic materials, and removing the lignin substantially continuously adjacent the point said hydrolyzing solution is introduced.

5. Apparatus for hydrolyzing cellulosic materials comprising a reaction chamber having negatively sloped side walls, means to introduce continuously cellulosic materials under pressure at one end of said reaction chamber, means to introduce continuously a hydrolyzing solution and steam adjacent the other end of said reaction chamber in counter-current flow to said cellulosic materials, means disposed adjacent the end of the reaction chamber into which said cellulosic materials are introduced to remove thereat the volatile products and sugar liquor, and means adjacent the end of the reaction chamber into which said hydrolyzing'solution is introduced to remove thereat the lignin separated in the reaction chamber.

6. Apparatus for hydrolyzing cellulosic materials comprising a vertically extending reaction chamber having downwardly flaring side walls at the upper portion thereof, the upper portion of said side walls forming a cone-shaped top and the lower portion of said side walls forming inverted cone shaped bottom, a filter screen adjacent the top of the reaction chamber secured to the inner surface of said side walls and spaced from said upper portion defining therebetween a second chamber, a vapor off-take conduit communicating with said second chamber adjacent the top thereof, a sugar liquor discharge conduit communicating with said second chamber adjacent the bottom thereof, means to introduce cellulosic material continuously under pressure adjacent the top of the reaction chamber, means to introduce continuously a hydrolyzing solution and steam adjacent the bottom of the reaction chamber in counter-current flow to said cellulosic material, and means to remove lignin substantially continuously adjacent the bottom of the reaction chamber.

'7. Apparatus for hydrolyzing cellulosic materials as defined in claim 6 in which the filter screen is provided with a plurality of openings sloping downwardly and inwardly with respect to the direction of the flow of cellulosic material.

8. Apparatus as defined in claim 6 in which the vapor take-off conduit and the liquor discharge conduit communicate with a liquor flash tank which in turn communicates with a scrubbing tower for removing the condensible and soluble constituents from the vapors.

9. Apparatus for hydrolyzing cellulosic materials as defined in claim 6 in which the means to introduce the cellulosic material comprises a vertically extending housing tapered inwardly toward the lower end thereof and communicating with the top of the reaction chamber, a vertically extending feed screw tapered inwardly toward the lower end thereof and rotatably mounted in said vertically extending housing, means to rotate said feed screw, a horizontally extending screw housing communicating at the discharge end thereof with the top of said vertically extending housing, an approach screw rotatably mounted in said horizontally extending housing, means to rotate said approach screw, and means to feed the cellulose material into said horizontally extending housing.

10. Apparatus as defined in claim 9 in which the horizontally extending housing is provided with a plurailty of openings in the bottom thereof for removing excess moisture.

11. Apparatus for hydrolyzing cellulosic materials comprising a vertically extending reaction chamber having downwardly and outwardly sloped side walls and a cone shaped top and bottom therefor, means to introduce cellulosic material continuously under pressure at the top of the reaction chamber, means to introduce continuously a hydrolyzing solution and steam under pressure adjacent the bottom of the reaction chamber in counter-current fiow to said cellulosic material, a filter cone secured to the inner surface of said side walls adjacent the top thereof and spaced from said cone shaped top defining therebetween a second chamber, a vapor off-take conduit and a sugar liquid discharge conduit communicating with said second chamber, a lignin discharge housing secured to and communicating with said cone shaped bottom of the reaction chamber, a poppet valve mounted in said housing and seating against said cone shaped bottom of the reaction chamber thus maintaining pressure within the reaction chamber, and means to intermittently move said valve to disengage said cone shaped bottom thus intermittently releasing pressure and causing the liquid contained in the lignin to flash into steam thereby discharging lignin from the reaction chamber.

12, Apparatus for hydrolyzing cellulosic materials as defined in claim 11 in which the discharge housing communicates with a lignin flash tank.

13. Apparatus for hydrolyzing cellulosic materials comprising a vertical reaction chamber having outwardly and downwardly sloped side walls, means to introduce continuously cellulosic material under pressure at the top of the reaction chamber, an acid pump and a water pump communicating with said reaction chamber at a common point adjacent the bottom thereof, a steam conduit communicating with the reaction chamber at a different point adjacent the bottom thereof, a filter screen secured to the inner surface of said side walls and spaced from the upper portion thereof to define a second chamber, a vapor oil-take conduit and a sugar liquor discharge conduit communicating with said second chamber, and means to remove lignin substantially continuously adjacent the bottom of said reaction chamber.

14. Apparatus for hydrolyzing cellulosic materials comprising a vertical reaction chamber having outwardly and downwardly sloped side walls and a cone shaped top and bottom therefor, means to introduce cellulosic material continuously under pressure at the top of the reaction chamber, a horizontally extending annular block adjacent the bottom of the reaction chamber having upper and lower annular passages therein, conduits for introducing separately a dilute hydrolyzing solution and steam, each of said conduits communicating with one of said annular passages, there being a plurality of upwardly extending, spaced apart openings communicating with the lower annular passage and the reaction chamber, there being a plurality'of upwardly extending openings communicating with the upper annular passage and the reaction chamber between the first mentioned upwardly extending openings, a filter screen secured to the inner surface of said side walls and spaced from the upper portion thereof to define a second chamber, a vapor off-take conduit and a sugar liquor discharge conduit communicating with said second chamber, and means to remove lignin substantially continuously adjacent the bottom of the reaction chamber.

15. Apparatus for hydrolyzing cellulosic materials comprising a vertically extending reaction chamber having downwardly flaring side walls, means disposed adjacent the top of said chamber to introduce continuously a cellulosic material under pressure, means disposed adjacent the lower end of the reaction chamber to introduce continuously a supply of hydrolyzing solution in counter-current flow to said cellulosic material, means disposed adjacent the upper end of said chamber to remove the volatile products and sugar liquor, and intermittently actuated discharge mechanism adjacent the bottom of the reaction chamber permitting the intermittent escape of quantities of lignin from the chamber.

16. The method of hydrolyzing cellulosic materials comprising introducing continuously cellulosic materials at the upper end of a downwardly moving column thereof while maintaining said column under superatmospheric pressure, introducing continuously a hydrolyzing solution and steam at the lower end of said column counter to the direction of movement of the cellulosic materials, expanding the volume of the cellulosic materials while passing the same counter to the direction of movement of the hydrolyzing solution thus causing the cellulosic materials to imbibe the hydrolyzing solution and form lignin, sugar solution and volatile materials, removing continuously the volatile materials and the sugar solution from the column adjacent the point of introduction of the cellulosic materials, intermittently releasing the pressure on the column at the lower end thereof and immediately following said release of pressure removing from the lower end a quantity of lignin thereby causing said column to move abruptly downward.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,677,406 Perl July 17, 1928 2,086,701 Dreyfus July 13, 1937 2,088,977 Scholler Aug. 3, 1937 2,108,567 Scholler Feb. 15, 1938 2,198,785 Mohr Apr. 30, 1940 2,426,677 Fulmer Sept. 2, 1947 FOREIGN PATENTS Number Country Date 117,256 Sweden July 18, 1946 367,916 Great Britain Feb. 22, 1932 58,383 Norway Sept. 6,, 1937 

6. APPARATUS FOR HYDROLYZING CELLULOSIC MATERIALS COMPRISING A VERTICALLY EXTENDING REACTION CHAMBER HAVING DOWNWARDLY FLARING SIDE WALLS AT THE UPPER PORTION THEREOF, THE UPPER PORTION OF SAID SIDE WALLS FORMING A CONE-SHAPED TOP AND THE LOWER PORTION OF SAID SIDE WALLS FORMING AN INVERTED CONE SHAPED BOTTOM, A FILTER SCREEN ADJACENT THE TOP OF THE REACTION CHAMBER SECURED TO THE INNER SURFACE OF SAID SIDE WALLS AND SPACED FROM SAID UPPER PORTION DEFINING THEREBETWEEN A SECOND CHAMBER, A VAPOR OFF-TAKE CONDUIT COMMUNICATING WITH SAID SECOND CHAMBER ADJACENT THE TOP THEREOF, A SUGAR LIQUOR DISCHARGE CONDUIT COMMUNICATING WITH SAID SECOND CHAMBER ADJACENT THE BOTTOM THEREOF, MEANS TO INTRODUCE CELLULOSIC MATERIAL CONTINUOUSLY UNDER PRESSURE ADJACENT THE TOP OF THE REACTION CHAMBER, MEANS TO INTRODUCE CONTINUOUSLY A HYDROLYZING SOLUTION AND STEAM ADJACENT THE BOTTOM OF THE REACTION CHAMBER IN COUNTER-CURRENT FLOW TO SAID CELLULOSIC MATERIAL, AND MEANS TO REMOVE LIGNIN SUBSTANTIALLY CONTINUOUSLY ADJACENT THE BOTTOM OF THE REACTION CHAMBER.
 16. THE METHOD OF HYDROLYZING CELLULOSIC MATERIALS COMPRISING INTRODUCING CONTINUOUSLY CELLULOSIC MATERIALS AT THE UPPER END OF A DOWNWARDLY MOVING COLUMN THEREOF WHILE MAINTAINING SAID COLUMN UNDER SUPERATMOSPHERIC PRESSURE, INTRODUCING CONTINUOUSLY A HYDROLYZING SOLUTION AND STEAM AT THE LOWER END OF SAID COLUMN COUNTER TO THE DIRECTION OF MOVEMENT OF THE CELLULOSIC MATERIALS, EXPANDING THE VOLUME OF THE CELLULOSIC MATERIALS WHILE PASSING THE SAME COUNTER TO THE DIRECTION OF MOVEMENT OF THE HYDROLYZING SOLUTION THUS CAUSING THE CELLULOSIC MATERIALS TO IMBIBE THE HYDROLYZING SOLUTION AND FORM LIGNIN, SUGAR SOLUTION AND VOLATILE MATERIALS, REMOVING CONTINUOUSLY THE VOLATILE MATERIALS AND THE SUGAR SOLUTION FROM THE COLUMN ADJACENT THE POINT OF INTRODUCTION OF THE CELLULOSIC MATERIALS, INTERMITTENTLY RELEASING THE PRESSURE ON THE COLUMN AT THE LOWER END THEREOF AND IMMEDIATELY FOLLOWING SAID RELEASE OF PRESSURE REMOVING FROM THE LOWER END A QUANTITY OF LIGNIN THEREBY CAUSING SAID COLUMN TO MOVE ABRUPTLY DOWNWARD. 